1. Field of the Invention
The present invention relates to a sealant dispensing method of a liquid crystal display (LCD) device, and more particularly, to a sealant dispensing method using a dispenser.
2. Discussion of the Related Art
Among various ultra-thin flat type display devices, which include a display screen having a thickness of several centimeters, a liquid crystal display (LCD) device can be widely used for notebook computers, monitors, aircraft, and etc. because it has advantages such as low power consumption and portability.
FIG. 1 is a cross sectional view of an LCD device according to the related art. As shown in FIG. 1, the LCD device according to the related art includes lower and upper substrates 1 and 3 facing each other at a predetermined interval therebetween, and a liquid crystal layer 5 formed between the lower and upper substrates 1 and 3.
Although not shown, the lower substrate 1 includes a thin film transistor TFT and a pixel electrode, and the upper substrate 3 includes a black matrix layer, a color filter layer and a common electrode.
In addition, a sealant 7 is provided between the lower and upper substrates 1 and 3 to prevent liquid crystal from leaking and bond the lower and upper substrates 1 and 3 to each other.
The sealant 7 is dispensed on any one of the lower and upper substrates 1 and 3 by either a printing method using a screen or a dispensing method using a dispenser. The printing method may have bad effects on an alignment layer formed on the substrate, because the screen contacts the substrate during the printing process. Recently, the dispensing method is generally used.
Hereinafter, a dispensing method according to the related art will be explained with reference to the accompanying drawings. FIG. 2 is a schematic view illustrating a sealant forming method using a dispenser according to the related art.
The dispenser is provided with a syringe 10, a nozzle 20, and a dispensing tube 30. The syringe 10 has a sealant 15 therein. The nozzle 20 is connected to a lower end of the syringe 10 to supply the sealant 15 to a substrate 1. The dispensing tube 30 is connected to an upper end of the syringe 10 to discharge the sealant 15 through the nozzle 20 by applying a pressure to the syringe 10.
A sealant forming method using the above dispenser will now be explained.
The dispenser moves along an arrow direction from a starting point(s) of the substrate 1, and then turns back to the starting point(s) of the substrate 1. During the movement of the dispenser, a predetermined pressure is applied to the syringe 10 through the dispensing tube 30 so that the sealant 15 is discharged to the substrate 1 through the nozzle 20. Accordingly, the sealant 15 is dispensed to the substrate 1.
After completion of dispensing the sealant 15, the dispensing tube 30 is closed to stop the discharge of the sealant 15. Thereafter, the dispenser is moved to a predetermined position and dispenses another sealant material according to the above-mentioned method to form a plurality of sealant patterns on the substrate 1.
However, the dispenser and sealant dispensing method according to the related art has the following disadvantages.
After completion of dispensing one sealant material, the dispensing tube 30 is closed to stop the discharge of the sealant 15 from the nozzle 20. At this time, the sealant may coagulate in the nozzle 20. Thereafter, when another sealant material is supplied to the substrate 1 through the nozzle 20, the coagulated sealant is discharged to the starting point of the substrate 1, thereby making it difficult to uniformly dispense sealant materials. Because of this problem, it has been necessary to start dispensing the sealant in a dummy region away from the panel area. This way any dried or coagulated sealant is dispensed away from the panel's sealant area. Sealant dispensing patterns include ribbon patterns or other starting paths in the dummy region. The problem with these solutions is that they require the dispensing of sealant across the scribing or cutting path on the substrate. Scribing or cutting through the hardened sealant can damage or wear out the scribing or cutting tool.